1999 Miata Engine For An RX-7
03-31-08, 07:31 PM
#26
make no mistake I agree with them, but after years of watching these ideas and buildups I've just come to the conclusion that it's not my place nor do I have the energy to worry about other peoples cars. In the end these are just cars...not idol to be worshipped, but other people disagree and will defend their car and what they think it represents. Do what you want, but don't expect us to like it...as long as it does what you want it to do then at least you should be happy and satisfied.
03-31-08, 07:53 PM
#27
i dont have a 'problem' with this kind of swap, per se, it just serioulsy makes zero sense. if this is indeed a serious post, the you must be tragically misinformed about one thing or another.
the cost alone of swapping that engine will outweigh the cost in gas for the life of the rotary. thats without a doubt. i'm assuming you don't know whats involved with a custom engine swap that has no support. at least with the v8 swaps, there are mounts available to buy and technical support.
the only reason i can see for this is that you like the looks of the FD but couldn't care less about performance. if that is the case, i think anyone would recommend you save the money for a rebuild (just in case), and just keep the engine stock.
any action you take on the car will outweigh the mph benefit by a long shot, if that is your only motivation.
the cost alone of swapping that engine will outweigh the cost in gas for the life of the rotary. thats without a doubt. i'm assuming you don't know whats involved with a custom engine swap that has no support. at least with the v8 swaps, there are mounts available to buy and technical support.
the only reason i can see for this is that you like the looks of the FD but couldn't care less about performance. if that is the case, i think anyone would recommend you save the money for a rebuild (just in case), and just keep the engine stock.
any action you take on the car will outweigh the mph benefit by a long shot, if that is your only motivation.
03-31-08, 08:08 PM
#28
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hm....not my cup of tea but i think there could be better motors to be dropped in if your going piston. Drop a supra motor in there. But to each his own. would be neat i guess!
04-01-08, 01:27 AM
#29
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I wouldn't do it because the amount of money it would cost to swap an engine that isnt easily compatible with the car is not going to save you money in gas due to the money you have to pour up front in order to do the swap which will run you 2k+, so unless you drive the car for a very very long time you wont see that savings for a very long time since the avg mpg of the rotary hovors around 20mpg, going to 30mpg give you an extra 10 mpg, but you need to save 2000 dollars in gas to justify it.
04-01-08, 07:25 AM
#30
53.6%/46.4% - Crap!
Look at it this way:
Negatives
-5k cost for the swap (probably a low-end figure unless you will be fabbing the kit yourself)
-FD is worth ~ 7k afterwards (a guess, based on the price of a roller)
-No power
-No torque
-Complicated and unsupported swap
Positive
-Increase? from 18/24 to 19/23 (That is the base automatic '99 Miata fuel economy (23/28) scaled by a factor of 2300/2800 for the added weight of the FD, although I don't know if that is a legitimate way of looking at it.)
So when you get down to it, you wasted 9k on this swap at least (5k swap cost + 4k loss in value on your car) and you have a negligible effect on fuel economy.
Why on Earth would you waste so much time and money for no gain? You could buy a mid-2000's Civic and keep the FD if you have 9k to blow on this. It isn't that we are being emotionally attached to the rotary, but there are far better options out there. An LS1 swap would be cheaper (with the swap cost and the loss of value on your car associated with the Miata engine swap) and it wouldn't have any of the drawbacks. You WOULD see close to 30 mpg highway if not more and have the reliability of a low mileage pushrod engine. At the end of the day your car went from being worth 11k (a guess, I don't know your mileage) to 20k. How do you not see this logic?
04-01-08, 08:36 AM
#31
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Lol, $5,000 for an engine swap... and I'm assuming that's above the cost of the 4 cylinder engine and tranny. This will probably result in a car that will do 0-60 in 12 seconds. It's your car... do it... your FD will be infamous! Please keep us updated on the project.
04-01-08, 01:28 PM
#35
Shane,
I never said I did'nt care. Believe me, you guys have all given excellent feedback. And I appreciate you all for that.
Okay, you are all againts the Miata engine swap in an FD. Other than a V8 what would you recommend it it were your FD?
I think it would still sound like a Mazda.
04-01-08, 04:46 PM
#39
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If you want 40MPG+ and like spending money on loosing performance how about a mercedes 95+ CDI diesel engine and trans.
These cars stock, or rather with nothing more than a chip can make like 280HP 380 TQ, and in an Rx7 should have no problem achieving 50 MPG (they get 35-40 in a car with ~1500 pounds more weight.
They also last forever. Should have no problem running 500K miles if maintained well, or 300K if maintained poorly and abused.
I would expect that you would be spending at least 10K on such a swap, probably more like 15K.
These cars stock, or rather with nothing more than a chip can make like 280HP 380 TQ, and in an Rx7 should have no problem achieving 50 MPG (they get 35-40 in a car with ~1500 pounds more weight.
They also last forever. Should have no problem running 500K miles if maintained well, or 300K if maintained poorly and abused.
I would expect that you would be spending at least 10K on such a swap, probably more like 15K.
Economical Swap
04-01-08, 07:21 PM
#41
If you want 40MPG+ and like spending money on loosing performance how about a mercedes 95+ CDI diesel engine and trans.
These cars stock, or rather with nothing more than a chip can make like 280HP 380 TQ, and in an Rx7 should have no problem achieving 50 MPG (they get 35-40 in a car with ~1500 pounds more weight.
They also last forever. Should have no problem running 500K miles if maintained well, or 300K if maintained poorly and abused.
I would expect that you would be spending at least 10K on such a swap, probably more like 15K.
These cars stock, or rather with nothing more than a chip can make like 280HP 380 TQ, and in an Rx7 should have no problem achieving 50 MPG (they get 35-40 in a car with ~1500 pounds more weight.
They also last forever. Should have no problem running 500K miles if maintained well, or 300K if maintained poorly and abused.
I would expect that you would be spending at least 10K on such a swap, probably more like 15K.
Is the mercedes 95+ CDI diesel engine a rear wheel drive?
04-01-08, 08:30 PM
#42
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Well, since all Mercedes are either rear or 4-wheel drive, I'm sure you could make it work. Granted diesels get better mileage and gobs of low end torque, but diesel also costs even more than premium right now (at least here it does).
04-01-08, 10:38 PM
#43
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yes of course it is the post above is correct. This one is actually just regular rear wheel drive. There should be little problem making this engine fit.
The cost of diesel at 15% above the cost of regular gas will have little impact on someone able to avg 45-50+ mpg combined.
I have an old 98 TDI VW jetta daily driver.. with really simple bolt on mods it should be making about 125 WHP and 250+ WTQ. While by no means fast compared to a stock FD or FC turbo, it could keep up with a stock NA.
It gets 54-56 MPG at 80 MPH, and never goes below 45 MPG no matter how I drive. A full tank of #2 diesel will get me way over 600 miles with plenty left.
In any case even with the greater cost of diesel it still doesn't matter.
The cost of diesel at 15% above the cost of regular gas will have little impact on someone able to avg 45-50+ mpg combined.
I have an old 98 TDI VW jetta daily driver.. with really simple bolt on mods it should be making about 125 WHP and 250+ WTQ. While by no means fast compared to a stock FD or FC turbo, it could keep up with a stock NA.
It gets 54-56 MPG at 80 MPH, and never goes below 45 MPG no matter how I drive. A full tank of #2 diesel will get me way over 600 miles with plenty left.
In any case even with the greater cost of diesel it still doesn't matter.
04-01-08, 10:59 PM
#44
before you do all of this why don't you just put the engine that's supposed to be in it drive it properly take care of it go single turbo something small like a td06-25g which is pretty much a replacement for the stock twins less headache's ect. Get a Power FC with a good tune it'll still wont be a honda civic when it comes to MPG's but still reasonable for what the car is or you can always go N/A....or you can do what falken did with their FD and put an SR20 in it and i would go with the S14 Silvia K's engine which was an N/A version of the SR20 and still put out a 170Hp which is not to shabby. Depends on your budget of course you look like you just want the shell of a FD so who cares what it sounds like or you can do the ultimate blasphemy and put an S2000 engine in it!...it'll sit far back just like the 13b so i don't think you'll mess up the weight distribution at all and you can always through the some odd parts in the back like the battery etc. Be creative if you got the money either way if you don't put a 13b in there you'll spend alot of custom fabrication. good luck...or sell me the roller for a good price i'll make good use of it 
04-02-08, 11:24 AM
#46
I just dont see the purpose of going with a Miata four in there... its a sports car, it was never meant to get great gas mileage. thats why i dont daily drive my FD.
Your better off buying a Miata and driving that around and keeping the FD for weekends and things.
Im not against swapping other engines into FD's, id never do it myself, but if your going to do that... you might as well keep it performance... considering that the FD3S IS a sports car and was designed specifically to BE a sports car. Otherwise you have basicly this HOT sports car that is SLOW and even then a miata engine in there wont garuntee good gas mileage, especially when its in a a car thats a good 600 - 800 pounds heavier than the car it came out of.
Your better off buying a Miata and driving that around and keeping the FD for weekends and things.
Im not against swapping other engines into FD's, id never do it myself, but if your going to do that... you might as well keep it performance... considering that the FD3S IS a sports car and was designed specifically to BE a sports car. Otherwise you have basicly this HOT sports car that is SLOW and even then a miata engine in there wont garuntee good gas mileage, especially when its in a a car thats a good 600 - 800 pounds heavier than the car it came out of.
04-02-08, 04:09 PM
#47
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The miata already handles well and can arguably outhandle an FD because of its more refined suspension, lighter weight, and smaller size. Autocross results typically show miatas, mr2s, and even the lowly mustang turning times similar to an FD with an equal driver.
The FD, with a miata engine, would probably be outperformed by the original car in both acceleration and cornering. The miata will also get better gas mileage.
If you want to keep the FD pure to its purpose, that being a high powered, mid sized GT type sports car and not the smallest, lightest possible go kart with license plates, any of the aluminum block GM V8s will produce a car that not only out accelerates the original FD, miata, or GM donor vehicle, but one that will also give you ~25mpg on the highway if you use the 6 speed transmission.
There is no reason to compete with the miata for gas mileage. If you already have a donor FD chassis, perhaps you want to keep it around because of its looks. That's understandable and in that case, the miata engine might make the car livable for a while until gas really gets expensive. But if you are trying to hedge against high gas prices, why not do an electric conversion? I've pondered an electric FD or mr2 more than a few times.
04-02-08, 05:35 PM
#48
My thoughts (from a V8 FC owner who has not driven a miata or FD much)
The miata already handles well and can arguably outhandle an FD because of its more refined suspension, lighter weight, and smaller size. Autocross results typically show miatas, mr2s, and even the lowly mustang turning times similar to an FD with an equal driver.
The FD, with a miata engine, would probably be outperformed by the original car in both acceleration and cornering. The miata will also get better gas mileage.
If you want to keep the FD pure to its purpose, that being a high powered, mid sized GT type sports car and not the smallest, lightest possible go kart with license plates, any of the aluminum block GM V8s will produce a car that not only out accelerates the original FD, miata, or GM donor vehicle, but one that will also give you ~25mpg on the highway if you use the 6 speed transmission.
There is no reason to compete with the miata for gas mileage. If you already have a donor FD chassis, perhaps you want to keep it around because of its looks. That's understandable and in that case, the miata engine might make the car livable for a while until gas really gets expensive. But if you are trying to hedge against high gas prices, why not do an electric conversion? I've pondered an electric FD or mr2 more than a few times.
The miata already handles well and can arguably outhandle an FD because of its more refined suspension, lighter weight, and smaller size. Autocross results typically show miatas, mr2s, and even the lowly mustang turning times similar to an FD with an equal driver.
The FD, with a miata engine, would probably be outperformed by the original car in both acceleration and cornering. The miata will also get better gas mileage.
If you want to keep the FD pure to its purpose, that being a high powered, mid sized GT type sports car and not the smallest, lightest possible go kart with license plates, any of the aluminum block GM V8s will produce a car that not only out accelerates the original FD, miata, or GM donor vehicle, but one that will also give you ~25mpg on the highway if you use the 6 speed transmission.
There is no reason to compete with the miata for gas mileage. If you already have a donor FD chassis, perhaps you want to keep it around because of its looks. That's understandable and in that case, the miata engine might make the car livable for a while until gas really gets expensive. But if you are trying to hedge against high gas prices, why not do an electric conversion? I've pondered an electric FD or mr2 more than a few times.
